U.S. patent number 4,721,137 [Application Number 06/916,332] was granted by the patent office on 1988-01-26 for apparatus for withdrawing liquid from closed receptacle.
This patent grant is currently assigned to Kontron Holding A.G.. Invention is credited to Paul Muller.
United States Patent |
4,721,137 |
Muller |
January 26, 1988 |
Apparatus for withdrawing liquid from closed receptacle
Abstract
An apparatus for withdrawing liquid from a receptacle which is
closed with a penetrable cover, which comprises a puncturing tool
for creating an aperture in the receptacle cover, a cannula for
entering the receptacle through the aperture and withdrawing liquid
from the receptacle, a holding arm to which the puncturing tool and
cannula are affixed in parallel and at a certain distance apart,
and a motor drive for effecting horizontal and vertical movements
of the holding arm relative to the covered receptacle to align,
lower and raise the puncturing tool and cannula in succession
through the cover.
Inventors: |
Muller; Paul (Steinhausen,
CH) |
Assignee: |
Kontron Holding A.G. (Zurich,
CH)
|
Family
ID: |
4274564 |
Appl.
No.: |
06/916,332 |
Filed: |
October 7, 1986 |
Foreign Application Priority Data
Current U.S.
Class: |
141/65; 141/276;
141/330 |
Current CPC
Class: |
G01N
35/1079 (20130101) |
Current International
Class: |
G01N
1/00 (20060101); B65B 003/04 () |
Field of
Search: |
;141/65,66,329,330,19,250-284 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
512147 |
April 1955 |
Taunton et al. |
|
Primary Examiner: Bell, Jr.; Houston S.
Attorney, Agent or Firm: Saxe; Jon S. Leon; Bernard S.
Mazza; Richard J.
Claims
I claim:
1. An apparatus for withdrawing liquid from a receptacle closed by
a penetrable cover, which comprises:
(a) puncturing tool means for puncturing the receptacle cover;
(b) cannula means for entering the receptacle through the aperture
produced by the puncturing tool means and withdrawing liquid from
the receptacle;
(c) holding arm means to which the puncturing tool means and
cannula means are commonly affixed in a parallel side-by-side
relationship at a certain distance from one another; and
(d) driving means for effecting horizontal and vertical movements
of the holding arm means relative to the receptacle cover and for
aligning the puncturing tool means with the receptacle cover such
that in a first of two vertical descents of the holding arm means
the puncturing tool means alone pierces the cover, thereby creating
a channel, and in a second vertical descent the cannula means
penetrates the cover through the channel previously created by the
puncturing tool means.
2. The apparatus of claim 1, in which the puncturing tool means has
a sharpened tip and is substantially cruciform in cross-sectional
shape.
3. An apparatus for withdrawing liquid from a receptacle closed
with a penetrable resilient cover, which comprises a horizontally
disposed base, a vertically disposed casing affixed to the base and
containing a mechanical driving means, a mobile support arm
extending at one end laterally from the casing and which is
substantially parallel to the base, a hollow pipetting head affixed
to the opposite end of the support arm, a puncturing tool rigidly
secured to and downwardly extending from the underside of the
pipetting head, a cannula rigidly secured to the same underside of
the pipetting head which is parellel to and spaced apart from the
puncturing tool and is in open communication with a suction means,
wherein the driving means is capable of moving the support arm and
pipetting head vertically along the length of the casing and
horizontally relative to the base.
Description
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for withdrawing liquid from a
receptacle closed by a cover.
To ensure sterility and to reduce difficulties connected with
solvent evaporation, reagents and samples for automatic analysis
systems are often provided in receptacles which are closed by a
resilient septum or by a plastic cover. Withdrawal of the liquid
contents of the receptacle is accomplished by means of a withdrawal
cannula which is connected by way of flexible piping to a pump and
which pierces the cover in order to dip into the body of
liquid.
To reduce the risk of contamination, analysis samples are often
dispatched or delivered in receptacles of this kind, and specimens
are withdrawn by means of a withdrawal apparatus with the use of an
appropriate cannula.
To ensure that the resilient cover, which is often in the form of a
rubber diaphragm, is punctured neatly the cannula must have a
special high-precision sharpening and so is relatively expensive.
Even then, it is often impossible to prevent the cannula from
becoming blocked by dislodged pieces of the diaphragm. Further, the
force required to puncture the diaphragm is relatively high despite
the special sharpening of the cannula tip, and so the pivot arms
and bearings experience elevated forces. Yet another disadvantage
is that the diaphragm engages sealingly with the cannula so that
when liquid is removed a negative pressure is generated in the
receptacle which has disadvantageous consequences; for example, the
negative pressure may impair sampling accuracy when sample
quantities are small.
It is an object of the present invention to disclose an improved
apparatus designed to avoid the above-mentioned disadvantages.
DESCRIPTION OF THE INVENTION
According to the present invention, in an apparatus for withdrawing
liquid a puncturing tool is disposed adjacent to and spaced apart
from the withdrawal cannula and means are provided for so
controlling the relative mechanical movements between the cannula
holder and the receptacle such that in a first descent of the
cannula holder the puncturing tool alone (not the cannula) is
aligned with and pierces the cover of the receptacle, after which a
relative lateral movement through a distance corresponding to the
distance between the puncturing tool and the cannula ensues, after
which in a second descent of the cannula holder the cannula alone
(not the puncturing tool) is aligned with and penetrates through
the previously made puncture or channel in the cover.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention will be described hereinafter with
reference to the accompanying drawings, wherein:
FIG. 1 is a diagrammatic view of a sampling apparatus, in
accordance with the present invention and
FIG. 2 is an inverted plan view of a portion of the apparatus of
FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
As shown in FIG. 1, a pipetting device in accordance with this
invention has a casing 1 which has a table-like bottom part or base
2. A liquid receptacle 3, from which it is required to pipette a
portion of liquid, is placed on base 2. The receptacle 3 is mounted
on frame 4, which is either stationary on base 2 or capable of
being moved thereon by a conveyor (not shown).
The receptacle 3 contains a liquid 5, such as a reagent, or test
specimen, or the like, and is closed by a resilient diaphragm 6
made, for example, of rubber, plastic, or the like.
A pipetting head 8, which functions as a holding means, is disposed
on arm 7 on the top part of casing 1 and has a downwardly extending
pipetting needle or cannula 9 and, disposed parallel to and at a
distance therefrom, a puncturing tool 7. A drive (not shown) is
adapted to move arm 7 as indicated by arrows, i.e., horizontally
and vertically. The drive mechanisms enabling pipetting apparatuses
to perform movements of this kind are known in the art and need
not, therefore, be described here in detail.
The needle 9 is a cannula which extends through head 8 and
communicates at the top with a flexible hose 11 which extends to a
pump.
The puncturing tool 10 is rigidly secured to the underside of head
8. Puncturing tool 10 is in cross-section substantially cruciform
and has a tip which has been ground to a sharp point. FIG. 2 is an
inverted plan view of tool 10.
In an actual system where not only one receptacle but a
multiplicity of receptacles arranged in a matrix-shaped array are
presented to the apparatus, it will be understood that an
appropriate number of cannulas and puncturing tools are associated
with the pipetting head.
The drive (not shown) for arm 7 carries out the following
mechanical cycle for each newly arrived receptacle:
I. The puncturing tool 10 is moved by an appropriate lateral
movement into a position in which it is aligned and substantially
concentric with the receptacle 3.
II. The arm 7 and, therefore, the tool 10 are lowered vertically to
puncture the diaphragm, the resulting puncture having a
substantially cruciform shape.
III. The arm 7 is raised to remove the tool 10 from the diaphragm.
The cruciform puncture closes like a simple valve.
IV. The arm 7 moves to the left relatively to the receptacle 3 by
an amount corresponding to the distance between tool 10 and the
cannula 9, to bring the cannula into alignment with and
concentrically above the receptacle 3.
V. The arm 7 descends to introduce the cannula 9 through the
previously produced diaphragm puncture into receptacle 3 and its
liquid contents 5, in order to intake liquid.
A number of advantages arise from separating the steps of
puncturing the diaphragm and engaging the cannula in the
receptacle. The puncturing tool can be of a material and shape such
that it requires much less force to puncture the diaphragm. The
resulting puncture has an accurate cruciform shape which, if
neither the puncturing tool nor the cannula is introduced,
immediately recloses substantially sealingly like a valve. Also,
the puncture can be so dimensioned due to the action of the shape
of the puncturing tool that when the cannula has been introduced
there are additional openings enabling pressure equalization with
the receptacle interior. Also, the cannula 9 does not need an
elaborately sharpened tip. Indeed, the cannula should even be blunt
because this has the additional advantage that the cannula fits
more accurately into the cylindrical sample injecting channel of a
conventional selector or sample input valve with practically no
distance to the valve rotor to reduce or virtually eliminate any
dead space in which a small liquid volume could otherwise be
captioned.
The drive makes no special requirements and can readily be devices
by the skilled worker in the manner known from conventional
pipetting apparatuses. The only point needing care is to ensure
that adjacent receptacles 3 are so disposed in spaced-apart
relationship to one another that sufficient space is available for
the cannula 9 when the tool 10 is making the puncture and
sufficient space is available for the tool 10 during pipetting.
Of course the embodiment described with reference to the drawings
merely represents one possible embodiment of the invention
modifications are possible. For instance, the invention could be
used in pipetting devices having any kind of pivoting arm. Also,
the relative lateral movement between, on the one hand, the
receptacle 3 and, on the other hand, the cannula and the puncturing
tool can be made by means of a receptacle conveyor instead of by
moving arm 7.
* * * * *